The present invention generally relates to firearms, and more particularly to systems used for camming the barrel under recoil after discharging the firearm and related methods for the same.
Firearms such as semiautomatic auto-loading pistols come in a variety of full size and compact platforms. Auto-loading pistols generally include a frame, an axially reciprocating slide mounted on the frame, and a barrel carried by the slide. One type of firing mechanism found in such pistols utilizes a pivotable spring-biased pivotable hammer which is held in a rear cocked and ready-to-fire position. To discharge the pistol, the hammer is released from a cocked position via a trigger pull which in turn impacts and drives a firing pin forward to contact and detonate a chambered ammunition cartridge. Alternatively, “striker-fired” pistols have a firing mechanism which utilize a linearly movable spring-biased striker that is held in a cocked position. Pulling the trigger releases the striker to directly contact and detonate a chambered ammunition round without the intervening firing pin.
In John M. Browning's early patent describing the mechanism of the Browning Hi-Power pistol (U.S. Pat. No. 1,618,510), he teaches a method of controlling the recoiling components of an autoloading pistol by means of a tilting barrel that uses a strictly linear cam surface on the barrel that engages a transverse pin (or surface of a cam block) that is attached to the frame. During the firing sequence of the pistol, the slide and barrel travel together during recoil in opposite reaction to the forward motion of the bullet and pressure generated by the deflagrating propellant. After the barrel and slide travel together for a short distance, the linear cam surface on the barrel engages the pin or surface of the cam block, and the barrel is pulled down and out of engagement with the slide. The barrel then stops and the slide continues to the rear, thereby allowing the empty cartridge case to be extracted from the now stationary barrel. As the slide continues its rearward travel, the pressure due to firing drops to zero (hence the force pushing the slide drops to zero) and the recoil spring compresses and begins to slow the slide. The cartridge case is ejected, and then the slide finally stops on the frame at its full rearward travel. The slide then returns forward due to the force of the recoil spring which is now returning to its original extended condition. In the process the slide strips a new round of ammunition out of the magazine, pushes it into the chamber of the barrel, pushes the barrel back up the linear cam and into its locked position with the slide, and then the slide/barrel group move the final distance forward into the firing position.
This linear cam system, invented in 1923, is used today in basically its original form as described by John Browning, and is the most popular short-recoil system in use for autoloading pistols. However, as ammunition performance has improved over the years, primarily in the development of large caliber, higher velocity cartridges that generate higher pressures, the original linear cam system described by Browning is proving to be insufficient as a means of controlling the velocity of the slide and hence the recoil force transmitted to both the pistol and the user.
An improved method of controlling slide velocity is needed that controls the velocity of the slide effectively while maintaining simplicity in design.